[ubuntu] Upgrade to 16 failed ppa launchpad not found

I'm trying to upgrade 15.10 on my laptop to 16.04 LTS and it fails with these errors;
Failed to fetch http://ppa.launchpad.net/ubuntu-nexu...amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/ubuntu-nexu...-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.

I ran, apt-get update, and tried again to update same problem.
I then ran, apt-get remove launchpad, not there so I installed it, same errors.

Not sure where to go from here.